1. Field of the Invention
The invention relates in general to transportation apparatus having movable handrails, and more specifically to transportation apparatus for transporting people between spaced landings, such as movable walks and escalators.
2. Description of the Prior Art
U.S. Pat. No. 3,712,447, which is assigned to the same assignee as the present application, discloses a handrail guide system for escalators and moving walks which eliminates the need for tensioning the handrail. A substantially continuous, closed-loop handrail guide system permits the handrail to be pushed as well as pulled about the guide loop. Suitable handrail drive arrangements for driving the handrail in such a system are disclosed in U.S. Pat. Nos. 3,414,109 and 3,779,360, which are assigned to the same assignee as the present application.
U.S. Pat. Nos. 3,707,220 and 3,677,388, which are assigned to the same assignee as the present application, disclose a modular passenger conveyor construction and a modular drive unit, respectively, with the latter being adapted for insertion into selected modular units of the former, in accordance with the requirement of the particular installation. The modular drive unit includes a sprocket on each side of the conveyor which is driven by an electric motor through a speed reducer. An idler sprocket is disposed on each side of the conveyor, adjacent to each driven sprocket, and a drive chain is reeved about each pair of driven and idler sprockets. The drive chain engages teeth on the conveyor to propel the conveyor about its closed loop.
A handrail drive pulley is mounted on an extension of the shaft of each driven sprocket, and a drive belt is reeved about this pulley and predetermined rotational elements of a handrail drive unit. Thus, the handrail on each side of the conveyor is driven in synchronism with the conveyor.
The handrail guide arrangement of U.S. Pat. No. 3,712,447 is carefully adjusted upon initial setup in an attempt to match its length with the length of the handrail loop, to reduce binding and frictional resistance of the handrail-guide interface. The loop length of the handrail may then change during usage due to manufacturing variations in the construction of the handrail, changes in the length of the handrail materials as the handrail flexes and wears, humidity, temperature, and the like. My U.S. Pat. No. 4,239,102 addresses this problem by disclosure of self-adjusting handrail apparatus, for accommodating temporary changes in loop length, such as those caused by humidity and temperature, reducing the frequency of readjustment of the handrail guide system. Thus, a smoothly operating handrail guide arrangement is provided when the handrail guide loop is correctly adjusted to provide low friction and freedom from binding, with the automatic adjustment accommodating temporary loop changes. It would be desirable to be able to quickly and accurately adjust the handrail guide loop to provide optimum low frictional resistance between the handrail and guide as the handrail is propelled about the guide loop.